Multi-tail hydrate inhibitors

ABSTRACT

Low-dosage hydrate inhibitor (“LDHI”) compounds comprising multiple lipophilic tails and a hydrophilic head may be employed into fluids to inhibit agglomeration of hydrates, among other things. Suitable hydrophilic heads may include quaternary or tertiary ammonium cation moieties, and combinations thereof. Such LDHI compounds in some embodiments may include reaction products of DETA and/or other amines, fatty acid(s), and, optionally, alkyl halide(s). Compounds according to some embodiments may be employed in fluids in various environments, such as a conduit penetrating a subterranean formation, or a conduit carrying fluid in an industrial setting.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 15/493,778 entitled “Multi-Tail Hydrate Inhibitors,” filed Apr. 21,2017, which is a divisional application of U.S. application Ser. No.14/891,018 entitled “Multi-Tail Hydrate Inhibitors,” filed Nov. 13,2015, now issued as U.S. Pat. No. 9,676,991 on Jun. 13, 2017, which is aU.S. National Stage Application of International Application No.PCT/US2014/036747 filed May 5, 2014, each which is herein incorporatedby reference in its entirety.

BACKGROUND

The present disclosure relates generally to compounds useful inprocesses involving fluid flowing through, or contained in, conduitssuch as pipes, such as the production of petroleum products, naturalgas, and the like. More particularly, the present disclosure relates tocompositions and the use of such compositions, such as in the inhibitionof the formation of gas hydrate agglomerates.

Gas hydrates are solids that may agglomerate in a fluid that is flowingor is substantially stationary, under certain temperature and pressureconditions. For example, gas hydrates may form during hydrocarbonproduction from a subterranean formation, in particular in pipelines andother equipment during production operations. Hydrates may impede orcompletely block flow of hydrocarbons or other fluid flowing throughsuch pipelines. These blockages not only may decrease or stopproduction, potentially costing millions of dollars in lost production,but also may be very difficult and dangerous to mediate. Unless properlyhandled, gas hydrates may be volatile and/or explosive, potentiallyrupturing pipelines, damaging equipment, endangering workers, and/orcausing environmental harm.

Gas hydrates may form when water molecules become bonded together aftercoming into contact with certain “guest” gas or liquid molecules.Hydrogen bonding causes the water molecules to form a regular latticestructure, like a cage, that is stabilized by the guest gas or liquidmolecules entrapped within the lattice structure. The resultingcrystalline structure may precipitate as a solid gas hydrate. Guestmolecules can include any number of molecules such as, for example,carbon dioxide, methane, butane, propane, hydrogen, helium, freon,halogen, a noble gas, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a compound that includes multiplelipophilic tails and a quaternary ammonium cation moiety in accordancewith aspects of the present disclosure.

FIG. 2 is a diagram illustrating an example reaction process inaccordance with aspects of the present disclosure.

FIG. 3 is a diagram illustrating an injection system that may be used inaccordance with certain embodiments of the present disclosure.

While embodiments of this disclosure have been depicted and describedand are defined by reference to certain embodiments, such references donot imply a limitation on the disclosure, and no such limitation is tobe inferred. The subject matter disclosed is capable of considerablemodification, alteration, and equivalents in form and function, as willoccur to those skilled in the pertinent art and having the benefit ofthis disclosure. The depicted and described embodiments of thisdisclosure are examples only, and are not exhaustive of the scope of thedisclosure.

DETAILED DESCRIPTION

Illustrative embodiments of the present disclosure are described indetail herein. In the interest of clarity, not all features of an actualimplementation may be described in this specification. It will of coursebe appreciated that in the development of any such actual embodiment,numerous implementation-specific decisions may be made to achieve thespecific implementation goals, which may vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthe present disclosure.

To facilitate a better understanding of the present disclosure, thefollowing examples of certain embodiments are given. In no way shouldthe following examples be read to limit, or define, the scope of theinvention. Embodiments of the present disclosure may be applicable tohorizontal, vertical, deviated, or otherwise nonlinear wellbores in anytype of subterranean formation. Embodiments may be applicable toinjection wells, monitoring wells, and production wells, includinghydrocarbon or geothermal wells.

Hydrate inhibitors are often grouped into 3 general classes:thermodynamic, anti-agglomerate, and kinetic hydrate inhibitors.Thermodynamic inhibitors are believed to operate by shifting the hydrateformation phase boundary away from temperature and pressure conditionsof a process by increasing the driving force required for formation ofthe hydrate. Such inhibitors may require high concentrations to beeffective (e.g., up to 50% or 60% inhibitor by amount of water). Kineticinhibitors and anti-agglomerate inhibitors may function at lowerconcentrations than thermodynamic inhibitors, and therefore may betermed low dosage hydrate inhibitors (LDHIs). Kinetic hydrate inhibitorsmay prevent or delay the nucleation of hydrates, thus limiting hydratecrystal size and growth. Anti-agglomerate LDHIs are believed to preventor otherwise disrupt the agglomeration of hydrates.

The present disclosure relates generally to compounds useful inprocesses involving fluid flowing through, or contained in, conduitssuch as pipes, such as the production of petroleum products, naturalgas, and the like. More particularly, the present disclosure relates tocompositions and the use of such compositions, such as in the inhibitionof the formation of gas hydrate agglomerates.

In some embodiments, the present disclosure may provide a low-dosagehydrate inhibitor (LDHI) compound comprising multiple lipophilic tails,a hydrophilic head, and a linking moiety. In some aspects, the presentdisclosure may also or instead provide salts of such compounds. Thepresent disclosure further provides methods of using such compoundsand/or salts thereof to inhibit the formation of one or more hydrates ina fluid. For example, some embodiments provide a method of inhibitingthe formation of hydrate agglomerates in a fluid comprising any one ormore of water, gas, hydrocarbons, and combinations thereof. Such amethod could include adding to the fluid an effective amount of acomposition comprising a compound according to the present disclosure,and/or salts thereof.

Among the many advantages provided herein, compounds and methods ofusing compounds according to the present disclosure may provide enhancedanti-agglomeration properties. For example, referring to embodimentsrelating to methods for inhibiting the formation of hydrateagglomerates: hydrate agglomeration may be inhibited to a greater degreethan that using conventional means, and/or a smaller quantity of LDHImay inhibit hydrate agglomeration. In particular embodiments, compoundsof the present disclosure may provide enhanced inhibition ofagglomeration of hydrates and/or hydrate-forming compounds.

The lipophilic tails according to some embodiments may eachindependently comprise a C₁ to C₅₀ hydrocarbon chain. As used herein, a“hydrocarbon chain” may, unless otherwise specifically noted, besubstituted or unsubstituted (that is, it may or may not contain one ormore additional moieties or functional groups in place of one or morehydrogens in the hydrocarbon chain); it may be branched, unbranched,acyclic, and/or cyclic; and/or it may be saturated or unsaturated.Furthermore, as used herein, the nomenclature “C_(x) to C_(y)” refers tothe number of carbon atoms in the hydrocarbon chain (here, ranging fromx to y carbon atoms).

A hydrocarbon chain on a lipophilic tail may be branched or unbranched,cyclic or non-cyclic, and may be any one or more of alkyl, alkenyl,alkynyl, and aryl groups, and/or combinations thereof. A lipophilic tailmay further optionally be substituted with any one or more additionalgroups, so long as such substituted additional group or groups do notalter the lipophilic and/or hydrophobic nature of the tail. Inparticular embodiments, a lipophilic tail may comprise (i) as few as anyone of: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,19, and 20 carbons, and (ii) as many as any one of: 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,28, 29, 30, 35, 40, 45, and 50 carbons. For example, suitable ranges ofcarbon atoms in the tail according to various embodiments include: 1 to5, 3 to 5, 4 to 8, 5 to 15, 8 to 18, 12 to 16, 8 to 20, 10 to 20, 15 to20, etc. In some embodiments, a lipophilic tail may be of identicalcomposition to any one or more other lipophilic tails of the compound.In other embodiments, each lipophilic tail may be of differentcomposition than any one or more other lipophilic tails.

In some embodiments, at least two of the lipophilic tails of thecompound are located at end-points of the compound. For example, asshown in FIG. 1, example LDHI compound 101 comprises two lipophilictails R¹ and R², each located at end-points of the compound 101. It willbe appreciated by one of ordinary skill in the art that even in suchembodiments, additional lipophilic tails could be included in thecompound (e.g., at a point along the backbone 105 of the compound 101linking the two lipophilic tails R¹ and R² together).

LDHI compounds of the present disclosure may further comprise ahydrophilic head. In some embodiments, a hydrophilic head may comprise acation moiety. In particular embodiments, a hydrophilic head maycomprise a cation moiety selected from the group consisting of:quaternary ammonium cation moieties and tertiary ammonium cationmoieties. Such a cation moiety may be embedded within the compound (thatis, bonded in two locations to other moieties of the compound), such asis shown with respect to hydrophilic head 115 of the compound 101 inFIG. 1. Thus, the cation moiety may be substantially of the composition—R³R⁴N⁺—. Each of R³ and R⁴ may comprise an organic moiety, such as ahydrocarbon chain comprising any one or more of: alkyl, alkenyl,alkynyl, aryl, arylalkyl, arylalkenyl, alkylaryl, alkenylaryl, glycol,and combinations thereof. Each of R³ and R⁴ may be branched or linear.Each R-group may be different, although in some embodiments the twoR-groups of a cation moiety may be identical. In particular embodimentswherein the cation moiety is a tertiary ammonium cation moiety, any oneof R-groups R³ and R⁴ may be H. Some embodiments may further include asecondary ammonium cation moieties. In such embodiments, both of R³ andR⁴ may be H. Nonetheless, in certain other embodiments, only one of R³and R⁴ may be H (that is, in certain embodiments the cation moiety mustbe a tertiary or quaternary ammonium).

Where any one or more R-group is not H, each R-group may be a C₁ to C₂₀hydrocarbon chain (excepting embodiments wherein the R-group comprisesan alkenyl or alkynyl group, in which case at least 2 carbon atoms arenecessary), or in other embodiments a C₂ to C₆ hydrocarbon chain, or inother embodiments a C₃ to C₆, or C₄ to C₈, hydrocarbon chain. Thus, anR-group of some embodiments may comprise a C₁ to C₁₀ alkyl chain, or inother embodiments a C₂ to C₆ alkyl, alkenyl, or alkynyl chain (branchedor unbranched), or in yet other embodiments a C₃ to C₆ alkyl, alkenyl,or alkynyl chain (branched or unbranched). Similarly, an R-group maycomprise a C₃ to C₁₀ aryl moiety (and likewise for C₃ to C₆ moieties).Some embodiments may include R-groups of smaller alkyl, alkenyl,alkynyl, or aryl groups, such as a group having at least 1 but not morethan 5, 4, 3, or 2 carbon atoms, in respective embodiments (with theabove-mentioned caveats for alkenyl, alkynyl, and/or aryl groups). Ahydrocarbon chain of an R-group according to various embodiments may beeither substituted or unsubstituted, and/or branched or unbranched,cyclic or non-cyclic. An R-group according to some embodiments may besubstituted (e.g., it may include other groups in addition to thehydrocarbon groups described above), so long as the cation moietyremains hydrophilic.

In certain embodiments, each R-group of a cation moiety may be smaller(e.g., contain fewer carbon atoms) than either of the lipophilic tailsof the compound.

The compounds of some embodiments may further include one or morelinking moieties. A linking moiety is any portion of the compound thatprovides spacing between a hydrophilic head and lipophilic tail. In someembodiments, the compound may comprise one linking moiety for eachlipophilic tail, each linking moiety providing spacing between thecorresponding lipophilic tail and a hydrophilic head. In particularembodiments, each of two or more lipophilic tails may each be separatedfrom a single hydrophilic head by each of two or more linking moieties,each linking moiety being bonded to the hydrophilic head. Returning forinstance to the compound 101 shown in FIG. 1, the hydrophilic head 115is separated from the first lipophilic tail R¹ by linking moiety 111,and from the second lipophilic tail R² by linking moiety 112. In someembodiments, a linking moiety may provide sufficient spacing so that thecompound overall maintains amphiphilic character. A linking moiety maycomprise any length hydrocarbon chain, branched or unbranched, again solong as the overall compound maintains amphiphilic character.Hydrocarbon chain lengths include C₁ to C₅₀ chains or longer. Forinstance, a linking group may be any one or more of methyl, ethyl,propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.Furthermore, a linking moiety may include any kind and number offunctional groups, again so long as the compound maintains bothhydrophobic and hydrophilic portions. Further, a functional groupincluded on a linking moiety according to some embodiments should notadversely affect the hydrophilic nature of a hydrophilic head, norshould it adversely affect the lipophilic nature of a lipophilic tail.Suitable functional groups that may be included in a linking moietyaccording to some embodiments may include any one or more of: an ester,sulfonamide, amide, ketone, carbonyl, isocyanate, urea, urethane, andcombinations thereof. In some instances, a functional group on a linkinggroup may include any group capable of reacting with an amine, again solong as that functional group's inclusion in the linking group allowsthe compound to maintain amphiphilic character. The compound 101 of FIG.1 includes examples of linking moieties 111, each comprising an amideand a carbonyl group, as well as an ethyl group.

LDHI compounds according to embodiments of the present disclosure mayinstead or in addition be characterized as reaction products. Forinstance, in some embodiments, the present disclosure provides acompound that may be characterized as the reaction product of: (1) anamide intermediate resulting from reaction between DETA(diethylenetriamine) and a stoichiometric amount of any one or morekinds of fatty acids; and (2) alkyl halide. Compounds according to suchembodiments will typically include a hydrophilic head comprising aquaternary ammonium cation. The R-group(s) of the quaternary ammoniumcation may depend upon the identity of the alkyl halide used. Similarly,the composition of the lipophilic tails of such compounds may dependupon the fatty acid(s) used. In particular embodiments, a fatty acid maylead to a mixture of different-length lipophilic tails in a singlemolecule of a compound, and/or as between two or more differentmolecules of the compound. In addition, a portion of a functional groupof the fatty acid(s) may be included in the linking moiety of theresultant reactant product. Suitable fatty acids for reaction mayinclude a saturated fatty acid and/or an unsaturated fatty acid, such asone or more selected from the group consisting of: corn oil, canola oil,coconut oil, safflower oil, sesame oil, palm oil, cottonseed oil,soybean oil, olive oil, sunflower oil, hemp oil, wheat germ oil, palmkernel oil, vegetable oil, caprylic acid, capric acid, lauric acid,stearic acid, myristic acid, myristoleic acid, palmitic acid,palmitoleic acid, stearic acid, sapienic acid, elaidic acid, vaccenicacid, linoleic acid, arachidic acid, arachidonic acid, eicosapentaenoicacid, erucic acid, docosahexaenoic acid, behenic acid, lignoceric acid,cerotic acid, oleic acids (cis- and trans-), and combinations thereof.

The reaction scheme of FIG. 2 illustrates an example of a compound (andits formation) according to some such embodiments. In the reactionscheme shown, 1 mole of DETA 201 reacts with 2 moles of fatty acid 205(which, as shown in FIG. 2, comprises hydrocarbon chain R¹), forming theamide intermediate 210. The amide intermediate 210 in turn reacts withalkyl halide 215 (comprising R³ as shown in FIG. 2) to form the LDHIcompound 220. As can be seen, LDHI compound 220 includes two lipophilictails R¹ (each retaining the hydrocarbon structure R¹ of the fatty acid)and a hydrophilic head 221 comprising an R-group R³ (retaining thehydrocarbon structure R³ of the alkyl halide). Such reactions may insome embodiments take place at about 80 to about 120° C. atapproximately atmospheric pressure. It will be appreciated by one ofordinary skill in the art that various modifications may be made to thisreaction scheme to produce other embodiments. For example, a mixture oftwo types of fatty acids comprising hydrocarbon chains R¹ and R²,respectively, could be used in the first reaction step, whereupon theamide intermediate (and therefore resulting LDHI compound) may include amixture of amides: some comprising two lipophilic tails, each havingstructure R¹; some comprising two lipophilic tails each having structureR²; and some comprising two lipophilic tails of mixed structure (e.g.,one R¹ and one R²). Furthermore, in yet other embodiments, anotherreactant besides fatty acid may be used. Examples of other reactantsinclude: esters, sulfonamides, amides, ketones, carbonyls, isocyanates,urea, urethane, and combinations thereof.

In some embodiments, the present disclosure may instead or in additionprovide salts of compounds as described herein. For example, thereaction product 220 as shown in FIG. 2 comprises a salt with a bromideion. Such salts may wholly or partially dissociate in aqueous solution.In other embodiments, the salts may remain substantially associated(either with the original anion or with other ions from solution). Itwill be appreciated by one of ordinary skill in the art with the benefitof this disclosure that salts may be formed with other anions instead ofor in addition to chloride anions. For instance, suitable anions maycomprise any one or more of hydroxide, carboxylate, halide, sulfate,organic sulfonate, and combinations thereof.

In some embodiments, LDHI compounds may be characterized as multi-tail,multi-amino organic compounds. For instance, compounds according to suchembodiments may have substantially the following structural formula:

Each of R¹ and R² may be a hydrocarbon chain according to previousdiscussion of lipophilic tails R¹ and R² (e.g., each may be a C₁ to C₅₀hydrocarbon chain, etc.).

Each of Z and Z′ may be moieties that comprise one or more functionalgroups and/or carbon chains independently comprising carbonyls. Incertain embodiments, each of Z and Z′ may comprise any functional groupcapable of reacting with an amine, but the inclusion of which in thecompound maintains the hydrophobicity of each of R¹ and R².

Each of L and L′ may be a C₁ to C₂₀ hydrocarbon chain. In certainembodiments, either or both of L and L′ may be unsubstituted. In otherembodiments, either or both may be substituted.

In particular embodiments, the moieties Z—NH-L and L′-NH—Z′ may each becharacterized as a linking group, and may in the aggregate be anylinking group in accordance with linking groups previously discussedherein.

M may be an amine or an ammonium cation moiety. In particular, M may beselected from the group consisting of R³N and R³R⁴N⁺, wherein each of R³and R⁴ may independently be selected from the group consisting of:hydrogen and a C₁ to C₁₀ hydrocarbon chain. Each of R³ and R⁴ in someembodiments may be in accordance with R³ and R⁴ discussed previouslywith respect to a cationic hydrophilic head. In embodiments wherein M isR³R⁴N⁺, that moiety may be associated (e.g., ionically bonded orotherwise associated) with an anion X, such that the compound has thestructural formula shown below:

X may be selected from the group consisting of halide, carboxylate,sulfate, organic sulfonate, hydroxide, and combinations thereof.

In certain embodiments, each one of the moieties R¹—Z and Z′—R² maycollectively be characterized as a moiety resulting from reactionbetween an amine and a fatty acid. In such embodiments, Z and Z′ areeach a carbonyl, and R¹ and R² each may be any hydrocarbon chainresulting from reaction of the amine groups having structureH₂N-L-NH-L′-NH₂ and the fatty acid or fatty acids. Thus, for example,each of R¹ and R² in such embodiments may be a hydrocarbon chainresulting from reaction of (i) an amine having the structureH₂N-L-NH-L′-NH₂ and (ii) a fatty acid selected from the group consistingof: corn oil, canola oil, coconut oil, safflower oil, sesame oil, palmoil, cottonseed oil, soybean oil, olive oil, sunflower oil, hemp oil,wheat germ oil, palm kernel oil, vegetable oil, caprylic acid, capricacid, lauric acid, stearic acid, myristic acid, myristoleic acid,palmitic acid, palmitoleic acid, stearic acid, sapienic acid, elaidicacid, vaccenic acid, linoleic acid, arachidic acid, arachidonic acid,eicosapentaenoic acid, erucic acid, docosahexaenoic acid, behenic acid,lignoceric acid, cerotic acid, oleic acids (cis- and trans-), andcombinations thereof. It should be noted that such embodiments mayinclude M as either R³N or R³R⁴N⁺, because (as described previously) thereaction product of amine and fatty acid may be further reacted (e.g.,with alkyl halide) to quaternize the central amine, but it need notnecessarily be so reacted. Either way, this latter reaction of suchembodiments may be carried out such that it does not affect the identityof R¹ and R² resulting from the former reaction between amine and fattyacid.

Compounds including multiple lipophilic tails and one or morehydrophilic heads according to the foregoing, and/or their salts, may besurfactants, and/or may have surfactant-like properties (such asamphiphilic qualities).

As previously noted, the present disclosure in some embodiments furtherprovides methods of using compounds according to the present disclosureto inhibit the formation of one or more hydrates. Thus, the presentdisclosure may provide a method of inhibiting the formation of one ormore hydrates in a fluid comprising any one or more of water, gas,liquid hydrocarbon, and combinations thereof, the method comprisingadding to the fluid an effective amount of an LDHI compound according tothe present disclosure. The LDHI compound may comprise multiplehydrophilic heads, a lipophilic tail, and a linking group, in accordancewith compounds discussed with respect to various embodiments herein. Thefluid may be flowing or it may be substantially stationary. In someinstances, the fluid may be in a high-pressure, low-temperatureenvironment.

Some embodiments may include introducing a composition comprising anLDHI compound as described herein (e.g., a compound that includesmultiple hydrophilic heads, a lipophilic tail, and a linking group),and/or a salt of such a compound, to a fluid comprising water and anyone or more of gas, liquid hydrocarbon, and combinations thereof.Although listed separately from liquid hydrocarbon, the gas may in someembodiments include gaseous hydrocarbon, though the gas need notnecessarily include hydrocarbon. The composition may be any suitablecomposition in which the LDHI compound may be included. For example, insome embodiments, the composition may be a treatment fluid for use in awellbore penetrating a subterranean formation during, for instance, oiland/or gas recovery operations. The composition may include a solventfor the LDHI compound. Suitable solvents include any one or more of:toluene, xylene, methanol, isopropyl alcohol, any alcohol, glycol, anyorganic solvent, and combinations thereof. The fluid may be within avessel, or within a conduit (e.g., a conduit that may transport thefluid), or within a wellbore and/or a subterranean formation. Examplesof conduits include, but are not limited to, pipelines, productionpiping, subsea tubulars, process equipment, and the like as used inindustrial settings and/or as used in the production of oil and/or gasfrom a subterranean formation, and the like. The conduit may in certainembodiments penetrate at least a portion of a subterranean formation, asin the case of an oil and/or gas well. In particular embodiments, theconduit may be a wellbore or may be located within a wellborepenetrating at least a portion of a subterranean formation. Such oiland/or gas well may, for example, be a subsea well (e.g., with thesubterranean formation being located below the sea floor), or it may bea surface well (e.g., with the subterranean formation being locatedbelowground). A vessel or conduit according to other embodiments may belocated in an industrial setting such as a refinery (e.g., separationvessels, dehydration units, pipelines, heat exchangers, and the like),or it may be a transportation pipeline.

Methods according to some embodiments may further include allowing theLDHI compound to concentrate at an oil-water interface in the fluid(e.g., an interface between water and gas in the fluid, and/or betweenwater and liquid hydrocarbon).

The compound in some embodiments may be introduced in an amount equal toabout 0.1 to about 5.5% volume based on water in the fluid (or in otherwords, about 0.1% to about 3.0% volume based on water cut). In variousembodiments, an effective amount of compound for inhibiting hydrates maybe as low as any of: 0.1, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75,2.00, 2.25, and 2.50% volume based on water cut. An effective amount maybe as high as any of: 0.50, 0.75, 1.00, 1.25, 1.50, 1.75, 2.00, 2.25,2.50, 2.75, 3.00, 3.25, 3.50, 3.75, 4.00, 4.50, 5.00, and 5.50% volumebased on water cut. Thus, in particular embodiments, an effective amountof compound for inhibiting agglomeration of hydrates may be about 0.1 toabout 3% volume based on water cut of the fluid; in other embodiments,about 0.1 to about 2% volume; in further embodiments, about 0.25 toabout 1.5% volume; and in yet other embodiments, about 0.5 to about 1.0%volume.

Furthermore, the compound in certain embodiments may be introduced toany of various fluids having different water cuts. For example, in someembodiments the water cut may be about 30 to about 50%. In otherembodiments, the water cut may be as low as any one of: 20, 25, 30, 35,40, 45, and 50%; while the water cut may be as high as any one of: 35,40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, and 95%. In certainembodiments, a fluid may have a water cut of 50% or more, 40% or more,or 30% or more, up to about 99%. In yet other embodiments, an LDHIcompound may be used in a fluid with any water cut ranging from about 1%to about 99%.

The hydrate inhibitors of the present disclosure may be introduced intoa well bore, subterranean formation, vessel, and/or conduit (and/or to afluid within any of the foregoing) using any method or equipment knownin the art. For example, these hydrate inhibitors may be applied to asubterranean formation and/or well bore using batch treatments, squeezetreatments, continuous treatments, and/or combinations thereof. Incertain embodiments, a batch treatment may be performed in asubterranean formation by stopping production from the well and pumpingthe dissolved hydrate inhibitors into a well bore, which may beperformed at one or more points in time during the life of a well. Inother embodiments, a squeeze treatment may be performed by dissolvingthe hydrate inhibitor in a suitable solvent at a suitable concentrationand squeezing that solvent carrying the hydrate inhibitor downhole intothe formation, allowing production out of the formation to bring thehydrate inhibitor to its desired location. In still other embodiments, ahydrate inhibitor of the present disclosure may be injected into aportion of a subterranean formation using an annular space or capillaryinjection system to continuously introduce the hydrate inhibitor intothe formation. In certain embodiments, a composition (such as atreatment fluid) comprising a hydrate inhibitor of the presentdisclosure may be circulated in the well bore using the same types ofpumping systems and equipment at the surface that are used to introducetreatment fluids or additives into a well bore penetrating at least aportion of the subterranean formation.

For example, a hydrate inhibitor of the present disclosure may beintroduced into a well bore and/or tubing using a capillary injectionsystem as shown in FIG. 3. Referring now to FIG. 3, well bore 305 hasbeen drilled to penetrate a portion of a subterranean formation 300. Atubing 310 (e.g., production tubing) has been placed in the well bore305. A capillary injection tube 330 is disposed in the annular spacebetween the outer surface of tubing 310 and the inner wall of well bore305. The capillary injection tube 330 is connected to a side-pocketmandrel 340 at a lower section of the tubing 310. A hydrate inhibitormay be injected into capillary injection tube 330 at the wellhead 308 atthe surface such that it mixes with production fluid at or near theside-pocket mandrel 340. As the production fluid flows through thetubing 310, the hydrate inhibitors may prevent the formation of one ormore hydrates within the tubing 310. Other capillary injection systemsand side pocket mandrel devices (e.g., those used in gas liftproduction) may be used in a similar manner to the system shown in FIG.3.

In certain embodiments, a hydrate inhibitor of the present disclosuremay be added to a conduit such as a pipeline where one or more fluidsenter the conduit and/or at one or more other locations along the lengthof the conduit. In these embodiments, the hydrate inhibitor may be addedin batches or injected substantially continuously while the pipeline isbeing used.

Once introduced into a fluid, subterranean formation, well bore,pipeline, or other location, the hydrate inhibitor may inhibit theformation of one or more hydrates within the fluid, subterraneanformation, well bore, pipeline, or other location.

In a first embodiment, the present disclosure may provide a method ofinhibiting the formation of hydrate agglomerates, the method comprising:introducing a composition into a fluid comprising (i) water and (ii) oneof gas, liquid hydrocarbon, and combinations thereof; wherein thecomposition comprises an LDHI compound, the LDHI compound having thestructural formula:

Each of R¹ and R² is a C₁ to C₅₀ hydrocarbon chain; each of Z and Z′ isa functional group capable of reacting with an amine, the inclusion ofwhich maintains hydrophobicity of each of R¹ and R²; each of L and L′ isa C₁ to C₂₀ hydrocarbon chain; and M is selected from the groupconsisting of R³N and R³R⁴N⁺, wherein each of R³ and R⁴ mayindependently be selected from the group consisting of: hydrogen and aC₁ to C₁₀ hydrocarbon chain.

In a second embodiment, the present disclosure may provide a methodaccording to the first embodiment, wherein each of Z and Z′ may bemoieties that comprise one or more functional groups and/or carbonchains independently comprising carbonyls.

In a third embodiment, the present disclosure may provide a methodaccording to any one of the first and second embodiments, wherein M isR³R⁴N⁺.

In a fourth embodiment, the present disclosure may provide a methodaccording to the third embodiment, wherein M is associated with an anionsuch that the LDHI compound has the structural formula:

In a fifth embodiment, the present disclosure may provide a methodaccording to the fourth embodiment, wherein the LDHI compound has thestructural formula:

In a sixth embodiment, the present disclosure may provide a methodaccording to any one of the third and fifth embodiments, wherein R³ is aC₄ to C₈ hydrocarbon chain and further wherein R⁴ is hydrogen.

In a seventh embodiment, the present disclosure may provide a methodaccording to any one of the foregoing embodiments, wherein each of R¹and R² is a C₈ to C₁₈ hydrocarbon chain.

In an eighth embodiment, the present disclosure may provide a methodaccording to any one of the foregoing embodiments, wherein the fluidresides within a conduit.

In a ninth embodiment, the present disclosure may provide a methodaccording to any one of the foregoing embodiments, wherein the fluid hasa water cut of about 30% to about 50%.

In a tenth embodiment, the present disclosure may provide a methodaccording to any one of the foregoing embodiments, wherein thecomposition is introduced in an amount such that the LDHI compound ispresent in the fluid in an amount equal to about 0.1 to about 3.0%volume based on water cut of the fluid.

In an eleventh embodiment, the present disclosure may provide a methodof inhibiting the formation of hydrate agglomerates, the methodcomprising: introducing a composition into a fluid comprising (i) waterand (ii) one of gas, liquid hydrocarbon, and combinations thereof,wherein the composition comprises an LDHI compound comprising multiplelipophilic tails, a linking moiety, and an ammonium hydrophilic headcomprising a quaternary ammonium cation having the structural formula:

wherein each of R³ and R⁴ is independently selected from the groupconsisting of hydrogen and a C₁ to C₁₀ hydrocarbon chain.

In a twelfth embodiment, the present disclosure may provide a methodaccording to the eleventh embodiment, wherein each lipophilic tail isindependently a C₈ to C₁₈ hydrocarbon chain.

In a thirteenth embodiment, the present disclosure may provide a methodaccording to any one of the eleventh and twelfth embodiments, whereinthe composition is introduced in an amount such that the LDHI compoundis present in the fluid in an amount equal to about 0.1 to about 3.0%volume based on water cut of the fluid.

In a fourteenth embodiment, the present disclosure may provide a methodaccording to any one of the eleventh-thirteenth embodiments, wherein thefluid resides within a conduit.

In a fifteenth embodiment, the present disclosure may provide a methodaccording to any one of the foregoing embodiments, wherein the LDHIcompound comprises the reaction product of a reaction between (i) anamide intermediate resulting from a reaction between diethylenetriamine(DETA) and one or more fatty acids; and (ii) alkyl halide.

In a sixteenth embodiment, the present disclosure may provide a methodaccording to the 15th embodiment, wherein the one or more fatty acidscomprises a fatty acid selected from the group consisting of: corn oil,canola oil, and combinations thereof.

In a seventeenth embodiment, the present disclosure may provide a methodaccording to any one of the foregoing embodiments, wherein the fluidresides within a subterranean formation.

In an eighteenth embodiment, the present disclosure may provide acompound having the structural formula

wherein each of R¹ and R² is a C₁ to C₅₀ hydrocarbon chain; R³ is a C₁to C₁₀ hydrocarbon chain; and X is an anion selected from the groupconsisting of halide, carboxylate, sulfate, organic sulfonate,hydroxide, and combinations thereof.

In a nineteenth embodiment, the present disclosure may provide acompound according to the eighteenth embodiment, wherein each of R¹ andR² is a C₁ to C₅₀ hydrocarbon chain resulting from reaction between anamine having structure H₂N—CH₂—NH—CH₂—NH₂ and a fatty acid, the fattyacid being selected from the group consisting of: corn oil and canolaoil.

In a twentieth embodiment, the present disclosure may provide acomposition comprising a compound having the structural formula

wherein each of R¹ and R² is a C₁ to C₅₀ hydrocarbon chain; R³ is a C₁to C₁₀ hydrocarbon chain; and X is an anion selected from the groupconsisting of halide, carboxylate, sulfate, organic sulfonate,hydroxide, and combinations thereof.

In a twenty-first embodiment, the present disclosure may provide acomposition according to the twentieth embodiment, wherein each of R¹and R² is a C₁ to C₅₀ hydrocarbon chain resulting from reaction betweenan amine having structure H₂N—CH₂—NH—CH₂—NH₂ and a fatty acid, the fattyacid being selected from the group consisting of: corn oil and canolaoil.

In a twenty-second embodiment, the present disclosure may provide acomposition according to the twentieth embodiment, further comprising asolvent selected from the group consisting of: toluene, xylene,methanol, isopropyl alcohol, glycol, and combinations thereof.

To facilitate a better understanding of the present disclosure, thefollowing example according to some of the embodiments is given. In noway should such example be read to limit the scope of the invention.

EXAMPLE

A. Methodology

Rocking cell tests were carried out on numerous samples of differentcompounds having structures according to some embodiments of the presentdisclosure. Rocking cell tests involve injection of oil, water, and LDHIcompound into a cell at representative conditions. Optionally,additional gas may be injected into the cell (e.g., to achieve a desiredworking pressure during the experiment). Each cell was of a fixed volumeand contained constant mass during the experiment; that is, oil, water,LDHI compound, and (in some cases) gas were injected at the beginning ofthe experiment, but thereafter the cell was closed to mass transfer inor out of the cell. Each cell also included a magnetic ball in the spacewhere fluids are injected. The ball aided in agitation of the fluidsduring rocking. In addition, magnetic sensors on both ends of the celldetected whether the magnetic ball's movements through the fluids werehindered during rocking, thereby indicating the presence of hydrates.The cell also permitted visual observation of its contents for formationof hydrates during the experiment.

Initially, amounts of oil, water, and LDHI compound were injected intothe cell so as to achieve the desired water cut (i.e., fraction ofaqueous phase in the total fluid) and LDHI compound dosage (volume % ofLDHI compound on water cut basis) of the experiment. As performed inthis instance, three different water cuts were used in each of 3different test runs for each sample: 30%, 40%, and 50%. Dosage for LDHIcompounds in all tests was 2.0% volume on water cut basis. Afterinjection of oil, water, and LDHI compound, gas was injected to reach adesired pressure (e.g., working pressure of a conduit of interest forevaluation of the LDHI compound, in this case around 2,000 psi). Gascomposition varied based upon the conditions that would be encounteredin the target conduit for the LDHI compound.

Following injection of the gas, the cell was closed and rocked forapproximately 2 hours to emulsify the fluids therein. Temperature isthen ramped down from 20° C. to 4° C. over a period of about 2 hours,and rocking is continued for around 14 hours after the temperaturereaches final temperature. The rocking is then stopped for a period oftime while the cell is horizontal (e.g., to simulate a system shut-in).This “shut-in” period lasts for at least 6 hours, varying only so thatthe re-start of rocking could be visually observed. Visual observationsof the contents of the cell are made throughout the tests, withparticular attention paid to the following three phases of the test: (1)initial cooling period; (2) pre-shut-in; and (3) restart followingshut-in. These three phases of the testing provide a basis for visualrating of the performance of the LDHI compound as a hydrate inhibitor.Visual ranking results in a score at each phase, based upon a scale of 1through 5 according to the criteria set forth in Table 1 below. Forsystems with dark oils additional confirmation may be required via thesignal from the magnetic proximity sensors' detection of movement of themagnetic ball.

TABLE 1 Rocking Cell Visual Rating Criteria for LDHI Hydrate InhibitorsGrade Description 5 No or Ultra-fine Hydrate Crystals; Fully FlowableSystem No visible deposits on cell body or sapphire window. Full liquidlevel. Single phase or multiple, easily dispersible phases (i.e., brine,oil & hydrates). Low viscosity liquid(s). Ultra-fine hydrate crystalparticle size (if present; hydrates may look like ‘milk’). 4 LargerHydrate Particles and/or More Viscous Liquid than Grade 5; FlowableSystem Small quantities of intermittent visible deposits on cell body orsapphire window Full liquid level. Single phase or multiple, easilydispersible phases (i.e., brine, oil & hydrates). Low liquid viscosity.Fine hydrate crystal particle size if present (≤2 mm). Weak hydratecrystal association if present. 3 System will Flow with DifficultyIntermittent visible deposits on cell body or sapphire window Fullliquid level. Liquid is viscous and slowly dispersible. Intermediateliquid viscosity. Fine hydrate crystal particles (≤2 mm). No largecrystals 2 System will Most Likely Plug Visible deposits on cell body orsapphire window Full or low liquid level. Visible hydrate crystaldeposits. Stuck ball. Large solid crystals (>3 mm) may break with strongagitation. 1 System will Plug Visible deposits on cell body or sapphirewindow Low liquid level. Stuck ball. Two phases, one will disperse.Exceedingly high liquid viscosity. Large agglomerations (>3 mm). Largesolid crystals do not break with strong agitation.

B. Testing of Particular LDHI Compound Samples

Samples were prepared including compounds with structures according tosome embodiments of the present disclosure. Samples prepared had thefollowing base structure:

Each sample had R¹ and R³ as defined in Table 2 below. In instanceswhere R¹ varied within a molecule of the compound and/or from onemolecule to another of the compound, the reactant fatty acid is insteadlisted (e.g., as in the case of Samples 1 and 2).

TABLE 2 Sample Multi-Tail LDHI Hydrate Inhibitors Samples Water CutWater Cut Water No. R1 R3 X⁻ Dose % 30% 40% Cut 50% 1 Corn Oil C₅H₁₁ Br⁻2.0% 3-5 3-5 1-2 2 Canola Oil C₅H₁₁ Br⁻ 2.0% 3-5 3-5 3-5 3 C₁₈H₃₇ C₄H₉Br⁻ 2.0% 1-2 — — 4 C₁₈H₃₇ C₅H₁₁ Br⁻ 2.0% 3-5 1-2 — 5 C₁₈H₃₇ C₆H₁₃ Br⁻2.0% 1-2 — — 6 C₁₈H₃₇ C₇H₇(Benzyl) Br⁻ 2.0% 1-2 — — 7 C₁₈H₃₇ C₈H₁₇ Br⁻2.0% 1-2 — — 8 C₁₂H₂₅ C₄H₉ Br⁻ 2.0% 3-5 3-5 3-5 9 C₁₂H₂₅ C₅H₁₁ Br⁻ 2.0%3-5 1-2 — 10 C₁₂H₂₅ C₆H₁₃ Br⁻ 2.0% 1-2 — — 11 C₁₂H₂₅ C₇H₇(Benzyl) Br⁻2.0% 3-5 1-2 — 12 C₁₂H₂₅ C₈H₁₇ Br⁻ 2.0% 1-2 — — 13 C₈H₁₇ C₄H₉ Br⁻ 2.0%1-2 — — 14 C₈H₁₇ C₅H₁₁ Br⁻ 2.0% 1-2 — — 15 C₈H₁₇ C₆H₁₃ Br⁻ 2.0% 1-2 — —16 C₈H₁₇ C₇H₇(Benzyl) Br⁻ 2.0% 1-2 — — 17 C₈H₁₇ C₈H₁₇ Br⁻ 2.0% 1-2 — —

As also indicated by Table 2, each sample was applied at the indicateddosage (2.0% v/v based on water cut) to fluids having one or more of 3different water cuts: 30%, 40%, and 50%. Where no grade is indicated fora water cut in Table 2, no test at that water cut was performed for thecorresponding sample. In general, samples that obtained a score of 3-5at 30% water cut were then tested at 40% water cut, and samplesobtaining a score of 3-5 at 40% were then tested at 50% water cut. Asshown by Table 2, Samples 2 (prepared from canola oil) and 8 (having aC₁₂ hydrocarbon chain of form C₁₂H) presented the best results, withscores of 3-5 at all three water cuts tested. This is followed by Sample1, prepared from corn oil, having a score in the 3-5 range at both the30% and 40% water cut tests, but a 1-2 range score in the 50% water cuttest.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered ormodified and all such variations are considered within the scope andspirit of the present invention. In particular, every range of values(of the form, “from about a to about b,” or, equivalently, “fromapproximately a to b,” or, equivalently, “from approximately a-b”)disclosed herein is to be understood as referring to the power set (theset of all subsets) of the respective range of values, and set forthevery range encompassed within the broader range of values. Also, theterms in the claims have their plain, ordinary meaning unless otherwiseexplicitly and clearly defined by the patentee.

What is claimed is:
 1. A composition comprising: at least one compoundhaving the structural formula:

wherein each of R¹ and R² is a C₁ to C₅₀ hydrocarbon chain; wherein eachof R³ and R⁴ is independently selected from the group consisting of:hydrogen and a C₁ to C₁₀ hydrocarbon chain; and wherein X is an anionselected from the group consisting of a bromide, a carboxylate, anorganic sulfonate, a hydroxide, and any combination thereof; and atleast one solvent selected from the group consisting of: toluene,xylene, methanol, isopropyl alcohol, glycol, and any combinationthereof.
 2. The composition of claim 1, wherein each of R¹ and R² is aC₁ to C₅₀ hydrocarbon chain resulting from reaction between an aminehaving structure H₂N—CH₂—NH—CH₂—NH₂ and a fatty acid.
 3. The compositionof claim 2, wherein the fatty acid is selected from the group consistingof: corn oil, canola oil, and any combination thereof.
 4. Thecomposition of claim 1, wherein R³ is a C₄ to C₈ hydrocarbon chain. 5.The composition of claim 1, wherein the compound is present in thecomposition in an amount equal to about 0.1 to about 3.0% volume basedon a water cut of the composition.
 6. The composition of claim 1,wherein the composition has a water cut of about 30% to about 50%. 7.The composition of claim 1, wherein: R³ is a C₄ to C₈ hydrocarbon chain;and X is a bromide anion.
 8. A composition comprising a fluid and a lowdosage hydrate inhibitor additive comprising: at least one compoundhaving the structural formula:

wherein each of R¹ and R² is a C₁ to C₅₀ hydrocarbon chain; wherein eachof R³ and R⁴ is independently selected from the group consisting of:hydrogen and a C₁ to C₁₀ hydrocarbon chain; and wherein X is an anionselected from the group consisting of a bromide, a carboxylate, anorganic sulfonate, a hydroxide, and any combination thereof; and atleast one solvent selected from the group consisting of: toluene,xylene, methanol, isopropyl alcohol, glycol, and any combinationthereof.
 9. The composition of claim 8, wherein each of R¹ and R² is aC₁ to C₅₀ hydrocarbon chain resulting from reaction between an aminehaving structure H₂N—CH₂—NH—CH₂—NH₂ and a fatty acid.
 10. Thecomposition of claim 9, wherein the fatty acid is selected from thegroup consisting of: corn oil, canola oil, and any combination thereof.11. The composition of claim 8, wherein R³ is a C₄ to C₈ hydrocarbonchain.
 12. The composition of claim 8, wherein the low dosage hydrateinhibitor additive is present in the composition in an amount equal toabout 0.1 to about 3.0% volume based on a water cut of the composition.13. The composition of claim 8, wherein the composition has a water cutof about 30% to about 50%.
 14. The composition of claim 8, wherein thefluid is selected from the group consisting of: water, a gas, a liquidhydrocarbon, and any combination thereof.
 15. The composition of claim8, wherein: R³ is a C₄ to C₈ hydrocarbon chain; and X is a bromideanion.